This item is so inaccurate as to be worthless. I tried this on myself and another person, following up with standard blood pressure readings as taken with a Welch-Allyn cuff sphygmomanometer for comparison using the same arm immediately after reading this unit. As an example, the Welch-Allyn read my blood pressure as 120/67, while this unit read my blood pressure as 220/154, nearly double that of my actual pressure. This isn't even within a reasonable range of error, and it would be funny if not so potentially tragic. Do NOT waste your money on this; it shouldn't even be legal to sell any instrument for medical use that is this unreliable. As a medical professional, I find offering products of this low quality for sale actually offensive.